A Fischer-Tropsch synthesis reaction involves the reaction of a synthesis gas composed of hydrogen and carbon monoxide in the presence of a solid catalyst to yield a mixture of paraffin and olefin hydrocarbons having a comparatively wide molecular weight distribution. Liquid hydrocarbons in particular are attracting attention as a clean-burning automobile fuel.
Fischer-Tropsch synthesis reactions are characterized as being extremely exothermic. For example, the calorific value per kg-mol of carbon monoxide in the following general formula (1) representing the synthesis of saturated hydrocarbons is about 40 Mcal.nCO+2nH2→—(CH2)n—+nH2O   (1)
Thus, one of the most important factors of processes involving the synthesis of liquid hydrocarbons using the Fischer-Tropsch synthesis method is the efficient removal of the heat of the reaction from the reactor.
Fixed bed heat exchange-type multi-tubular reactors, fluidized bed reactors and slurry bed reactors have been proposed as types of Fischer-Tropsch synthesis reactors that enable industrial synthesis of liquid hydrocarbons from the synthesis gas while removing the heat of the reaction. Here, a slurry bed reaction system is a fluid reaction system in which three phases consisting of solid, liquid and gas phases are present that introduce the synthesis gas into the suspension of a liquid medium and catalyst particles, and it is remarkably advantageous in comparison with other fixed bed systems in terms of the uniformity of temperature profile in the reactor.
The use of a bubble column-type reactor has been advocated for slurry bed Fischer-Tropsch synthesis reaction systems, and catalyst particles are maintained in a suspended state in the form of a slurry by kinetic energy of the synthesis gas that rises from the bottom of the reactor in such a reactor(see, for example, Patent Documents 1 to 3).
One of the major subject of a bubble column-type slurry bed reaction system in which solid, liquid and gas phases are present is how the liquid hydrocarbon products can be efficiently separated and derived from the three-phase slurry, and the use of filtration separation in the main reactor (see, for example, Patent Documents 3 and 4), filtration separation in a separate vessel connected to the main reactor with a conduit (see, for example, Patent Document 5), and hydrocyclone separation (see, for example, Patent Document 6) have been advocated for this purpose.
Patent Document 1: European Patent No EU 450,860
Patent Document 2: U.S. Pat. No. 6,348,510
Patent Document 3: U.S. Pat. No. 6,462,098
Patent Document 4: U.S. Pat. No. 5,844,006
Patent Document 5: U.S. Pat. No. 5,770,629
Patent Document 6: U.S. Pat. No. 6,121,333